The talks, held this week in the Venezuelan capital Caracas, are the latest attempt by Colombia's leftist President Gustavo Petro to end six decades of conflict between the government and rebel groups.

As part of the ceasefire deal, Segunda Marquetalia committed to the "delivery of the people they are holding", according to a document signed by chief government negotiator Armando Novoa and rebel representative Walter Mendoza.

"The full implementation of de-escalation will begin as soon as the presidential decree on offensive military operations comes into force," said the text seen by AFP, without specifying a date.

A meeting in Tumaco, in western Colombia, will be held between the two parties "no later than July 20" to present the "de-escalation" agreement and to define a timetable for identifying social and economic projects.

The accord follows days of negotiations in Caracas, where seven delegates from each side began talks Monday.

Segunda Marquetalia is a rebel group that broke away from a historic 2016 ceasefire deal with FARC guerillas.

Those present at the Caracas talks include the rebels' leader known under the alias Ivan Marquez, who was thought to be dead until he reappeared in a video in May.

Marquez -- whose real name is Luciano Marin -- was the chief FARC negotiator for the 2016 deal, returned to civilian life and was elected a senator, before launching a new rebellion in 2019.

But at the opening of the Caracas talks, he said that he was "fully willing to contribute to the common achievement of peace for Colombia."

- Rebels to disarm -

Saturday's agreement stipulates that the rebel group agreed "not to remain armed or in uniform" in urban centers or "land and river routes."

It also asserts that the ceasefire does not restrict the national security forces' "constitutional and legal powers."

Colombia's leadership has faced multiple obstacles in their efforts to end the conflict between the country's security forces, guerrillas, right-wing paramilitaries and drug gangs.

The government and Segunda Marquetalia announced in February plans to hold peace talks.

The rebel group is considered second in importance only to the main FARC dissident group, the EMC, with Segunda Marquetalia having around 1,600 members according to military intelligence.

Talks between the government and the EMC began in October 2023 but they have been plagued by ceasefire violations and a major split in the group in April, which saw half of its fighters abandon peace negotiations.

The Colombian government has been involved since 2022 in stop-start talks with the Marxist National Liberation Army (ELN) -- responsible for the kidnapping last October of the father of a Liverpool footballer, Luis Diaz.